The United States and the rest of world are increasingly relying on natural gas for heating homes and buildings, generating electric power for residential and industrial applications, and as a feedstock for a variety of synthetic organic chemicals. Future demand for natural gas could grow even more dramatically as more new cars and trucks use electric power. Natural gas will likely play a major role in generating the electricity used in charging vehicle batteries, and supplying the methane and hydrogen used in operating vehicle fuel cells. Because the already high demand for natural gas is expected to soar, concerns about supply are growing.
One proposed solution is to build more long haul infrastructure to move natural gas where demand is greatest. Because natural gas is a gas at room temperature, there are more challenges in transporting it than for fuels like oil, coal and gasoline. The current leading proposal is to cool the gas to temperatures where it liquefies and transport the liquid natural gas (“LNG”) on refrigerated tankers. At the destination port, the LNG is warmed back into a gas that gets fed into the existing gas pipeline infrastructure. This proposed solution has been criticized for a number or reasons, including the significant cost associated with condensing and transporting LNG. There are also serious safety concerns about accidents and sabotage to the LNG infrastructure. These concerns have lead to strong local opposition to proposed sites for building a LNG port. In addition, some have argued that importing LNG only increases dependence on foreign sources of natural gas from politically unstable regions.
Another proposed solution is to explore and develop more sites for local natural gas production. In the United States, one site believed to contain large, untapped reserves of natural gas is the Arctic National Wildlife Refuge (“ANWR”) in Alaska. But proposals to develop this site, as well as other sites in the Rocky Mountain region of the United States, have been strongly opposed by environmental groups. Thus, development of new sources of local natural gas also faces significant limitations.
One way to avoid the problems with importing natural gas and developing new sites is to enhance gas production from existing local sites. One promising technology for doing this is microbially enhanced methane production. This technology uses microorganisms to metabolize complex organic substrates such as oil or coal into simpler compounds like methane and hydrogen. Stimulating the right indigenous microorganisms or introducing the right microorganisms under the right conditions to “retired” oil fields and coal deposits that are too deep to mine could turn these sites into productive new sources of domestic natural gas.
Because only a small fraction of the oil and coal was recovered from these sites while they were operating, the amount of hydrocarbon substrate still available for microbial conversion is enormous. The mature coal mines in the Powder River Basin in Wyoming, for example, are still estimated to have 1,300 billion short tons of unmined coal. If just 1% of this coal could be microbially converted into natural gas, it could supply the current annual natural gas need of the United States for four years. This story could be repeated at many other mature coal and oil sites across the country.
But the technology of microbial natural gas generation is still in its infancy. Many of the microorganisms require an anoxic or microoxic environment and are difficult to study in a conventional microbiology laboratory. While metabolic pathways have been postulated for breaking down a complex hydrocarbon substrate into natural gas and hydrogen, few specific microorganisms that are involved in methanogenic hydrocarbon biodegradation have been positively identified. The “first bite” microorganisms, which start the initial breakdown of complex hydrocarbon substrate into smaller molecules, have been particularly elusive.
Thus, there is a need for identifying microorganisms involved in biogenic gas production in underground hydrocarbon formations such as coal mines and oil fields. The identity of these microorganisms will provide valuable insight into how complex hydrocarbons are converted into fuel gases like hydrogen and methane. This insight can lead to methods of isolating, cultivating, and stimulating the microorganisms to make fuel gases at commercially viable production rates. These and other issues are addressed by the present invention.